Stalk Borer Movement
Growing Degree Day (GDD) accumulations can help growers monitor stalk borer hatch and movement by using GDD accumulated with a developmental threshold of
41º F. Common stalk borer eggs typically begin to hatch at 575 GDDs. They wrap up first hatch and begin feeding on weeds and grasses at 750 GDDs. At 1,300 GDDs, the first 10 percent of caterpillars begin to move into the corn crop and scouting should begin. At 1,400 GDDs, 50 percent of the caterpillars will have moved into corn.
The chart offers stalk borer scouting recommendations.
Common Stalk Borer Caterpillar Activity Based on Accumulated Degree Days
|Accum. Degree Days||Common Stalk Borer Caterpillar Activity||Recommendation|
|0-574||Conditions favorable for egg hatch.||No scouting necessary.|
|575-749||Eggs begin to hatch.||No scouting necessary.|
|750-1299||Young caterpillars begin boring into grass and weeds.||No scouting necessary. Avoid spraying grass and weeds along field edges.|
|1300-1399||10% of caterpillars begin moving into adjacent corn.||Begin scouting field edges for defoliation.|
|1400-1700||50% of caterpillars moving into adjacent corn.||Continue scouting for defoliation along field edges. Spray if necessary.|
|Source: South Dakota State University.|